1. Field of the Invention
The present invention relates to a roll grooving apparatus, and in particular, to tools that create circumferential grooves in pipes to allow the pipes to be connected together end to end using mechanical couplings.
2. Description of the Prior Art
Mechanical couplings are used to couple pipes to one another by creating a fluid tight joint. It is well known that such couplings are placed in circumferential grooves near the ends of adjoining pipe segments. The grooves are positioned in spaced relation to the ends of the pipe segments and are sized to receive arcuately shaped keys extending from each pipe segment. Engagement of the keys with grooves helps the joint formed by the coupling to maintain rigidity. Assembly of piping networks using mechanical pipe couplings may require that pipe stock be cut to a desired length, the cut pipe segments be reamed to remove burrs and sharp edges, and grooves be formed in both ends of each cut pipe segment. The cut, reamed and grooved pipe segments may then be joined to one another using the couplings.
Forming circumferential grooves in pipes that are made of malleable materials such as plastics, copper, steel and aluminum can be accomplished by cold working the material beyond its yield limit, thereby causing a permanent deformation in the material. Existing techniques for forming circumferential grooves in metal and plastic pipes entail sandwiching the pipe sidewall between the circumferences of two adjacent rotatable rollers. One roller, known as the backup roller, is positioned on the inside of the pipe, and the other, known as the grooving roller, is positioned on the outside in a position opposite the backup roller. The backup roller is concave around its outer circumference and the grooving roller is convex around its outer circumference. With the pipe sidewall between them, the rollers are rotated in opposite directions and are forced toward one another so that they apply pressure to the sidewall as the pipe segment rotates. The grooving surfaces traverse the pipe circumference and cooperate to cold work the sidewall producing a circumferential groove of a desired size and shape. The rollers may move around the pipe, in one version of this machine, or the pipe may rotate about its longitudinal axis and move relatively to stationary, but rotating rollers.
The method using a grooving roller and a back-up roller is effective at forming grooves in pipe walls while maintaining the roundness of the pipe because the pipe sidewall is mutually supported between the rollers and is never subjected to offset compressive loads which would tend to collapse the pipe or force it out of round. Both rollers cooperate to work the pipe sidewall, the grooving roller forming the groove and the back-up roller acting as a die to control the flow of material during cold working and precisely define a groove shape.
Our world-wide research of patent literature resulted in the following references which Applicant considers relevant to the herein described and illustrated invention. However, this prior art does not fairly teach or define the novel subject matter of the present invention, each alone, or in combination.
Dole, U.S. Pat. No. 6,993,949 discloses a pipe grooving tool with a housing on which a back-up roller and a grooving roller are rotatably mounted. The grooving roller is pivotable toward the back-up roller and has a raised tool surface engagable with the outer surface of the pipe. The pipe is positioned with its sidewall between the rollers, and the back-up roller is rotated while the grooving roller is forcibly moved toward the back-up roller. A circumferential groove is formed around the pipe as the rollers traverse its circumference. A power drive shaft connected directly to the back-up roller is provided, the power drive shaft engaging a power drive unit on which the tool is mounted operated under power. A manual drive shaft is connected to the back-up roller through a torque multiplying gear and pinion transmission for manual operation of the tool.
Hamm et al., U.S. Pat. No. 6,708,545 discloses a hydraulically operated roll grooving apparatus comprised of a vertically oriented idler and backup grooving rolls, each rotatable about a corresponding roll axis; a fluid actuator for displacing the idler roll toward the backup roll, a manually operated pump for supplying fluid under pressure to the fluid actuator, and a stabilizer for stabilizing a pipe being roll grooved. The pump and stabilizer are mounted on the same side of the apparatus with respect to the roll axes, and the pump has a vertically oriented major dimension and a pump operating lever including a removable handle.
Williams, U.S. Pat. No. 6,408,664 discloses a cold rolling apparatus which includes a forming roll, so as to apply a forming load to a tube when cold rolling the tube, and a hydraulic positioning assembly, this includes a positioning roller disposable for initial contact with a tube surface and is arranged to apply a positioning load to the tube. A hydraulic circuit is coupled to the forming roll and to the hydraulic positioning assembly such that the positioning load is related to the forming load. A face plate mounted for movement with the forming roll, and the positioning roller is mounted to the face plate. The face plate is coupled to a piston of the hydraulic positioning assembly for movement with the piston relative to the forming roll. The piston is housed within a cylinder body coupled to a guide block which is coupled to the forming roll. The forming roll is an outside roll, and the cold rolling apparatus includes two positioning rollers.
Hamm, U.S. Pat. No. 6,272,895 discloses facilitating a roll grooving apparatus for rolling a circumferential groove in a pipe; which is adapted to be mounted on a power drive unit for the axes of the driven and idler grooving rolls to lie in a plane, which is one of horizontal or at an acute angle to horizontal, such that the weight of a pipe between the grooving rolls, during a roll grooving operation, promotes tracking of the groove. A rotatable groove depth gauge is mounted on a support member of the apparatus adjacent to a stop element which engages the support member to determine groove depth, and the gauge is displaceable relative to the stop element into and out of a gauging position in which the stop element can be set to control the groove depth in a given workpiece.
Lippka, U.S. Pat. No. 5,778,715 discloses a positioning roller assembly, so as to be used when cold rolling a tube, which includes first and second positioning rollers disposed for initial contact with a tube surface, and a mechanism for maintaining contact of the first and second positioning rollers are relative to the tube surface during groove rolling. The first positioning roller is positioned to apply a first initial predetermined load to the tube and the second positioning roller is positioned to apply a second, smaller initial predetermined load to the tube. The mechanism acts on the tube in a manner to equalize the loads to offset the tube during cold rolling. The positioning rollers also apply a downward load to the tube during cold rolling to, e.g., reduce tube end flaring when cold rolling a groove in a steel pipe and stabilize a cold rolling machine when cold rolling outward steps in a copper pipe.
McGrady, U.S. Pat. No. 5,528,919 discloses with an apparatus for roll grooving thin wall pipe which is comprised of a housing so as to support a female drive roll and an arm, which is pivotally mounted on the housing, supports a male idler roll. A feed screw between the housing and arm provides for pivoting the arm to displace the idler roll radially toward and away from the drive roll, and a quick release arrangement between the feed screw and housing is operable to release the arm to displace the idler roll away from the drive roll at the end of a roll grooving operation without rotating the feed screw. Self-tracking during a roll grooving operation is provided by teeth on an outer surface of the drive roll which urge the pipe and grooving rolls axially inwardly relative to one another.
Pulver et al., U.S. Pat. No. 5,079,940 discloses a roll grooving apparatus is pivotally mountable on the support rails of a power drive unit; by which the apparatus is driven, it is comprised of a lower support which includes a drive shaft driven by the power unit and the lower grooving roll, and an upper support member pivotally interconnected with the lower support member and rotatably supporting the upper grooving roll. A lever arm is pivotally mounted on the lower support member and is interengaged with the upper support member through a pin and slot arrangement, whereby pivotal displacement of the lever arm imparts pivotal displacement to the upper support member and thus movement of the upper grooving roll toward and away from the lower grooving roll. The lower support includes a stop which limits displacement of the lever in the direction which moves the upper grooving roll towards the lower grooving roll, thus to assure a desired depth for the groove in a workpiece, and the pivotal interconnection between the upper and lower supports is adjustable to provide for adjusting the groove depth and accommodating different pipe or tube sizes and thicknesses. The adjustment enables using the stop on the lower support member as a constant in connection with pipe size and thickness variables and enables optimizing the leverage advantage and the direction of application of force of the upper grooving roll relative to the lower grooving roll.
Goodman, U.S. Pat. No. 4,166,370 discloses a single electric motor is employed to drive two separate backup roll supporting shafts which are mounted to rotate about a common horizontal axis. A first, solid, cylindrical backup roll of relatively small diameter (less than 1½″) is secured to one end of one of said shafts for rotation beneath a first grooving roll, and a second, relatively larger diameter backup roll (greater than 1½″ and less than 2″), which is annular in configuration, is secured coaxially to one end of the other shaft for rotation thereby beneath a second grooving roll. Each grooving roll is mounted for vertical reciprocation by springs and by a hydraulic ram supplied by fluid from a separate hand pump. Means is also provided for adjustably limiting the descent of each backup roll.
Elkin, U.S. Pat. No. 4,041,747 discloses an apparatus for grooving pipe extending longitudinally axially is there comprised of: a transversely elongated frame adapted to be displaced transversely relative to the pipe axis, a grooving roller which has an annular boss to swage the groove in the pipe, and a back-up roller which has an annular recess in transverse alignment with said boss, said rollers carried by the frame, and means to bodily and progressively displace one of the rollers relatively toward the other roller to cause the boss to progressively form the groove in the pipe wall being rotated between the rollers, the two rollers being rotated in response to pipe rotation.
Kunsman, U.S. Pat. No. 3,995,466 discloses a machine for semi-automatic grooving of pipe, which is capable of high output of full, or less than full, lengths of pipe with uniform external circumferential grooves; has supporting idler rolls for automatic positioning of the pipe axis at a small angle of deflection to draw the pipe end in as grooving progresses, with respect to a driven backup roll and a freely rotatable grooving roll. Pipe vibration during rotation is damped by hydraulic means. An adjustable groove depth control and a safety mechanism are also provided.
Thau, Jr. et al., U.S. Pat. No. 3,903,722 discloses a tool for rolling external circumferential grooves in pipes by rotating the pipe between a driven backup roll and a freely rotating grooving roll which engages the outer pipe surface. The grooving roll is mounted in a sliding housing and is urged against the pipe wall by a hydraulic cylinder acting along a line substantially perpendicular to the axis of rotation of the grooving roll. The linear motion of the sliding housing is limited by an adjustable depth stop to produce grooves of uniform depth.
Halliburton, U.S. Pat. No. 3,541,826 discloses a device for preparing the ends of lengths of pipe for coupling together, which simultaneously rolls a groove into the pipe wall, which is adjacent to the free end thereof and swages the end circumferentially inwardly.
Saito et al., U.S. Pat. No. 3,500,671 discloses a rolling apparatus for manufacturing rings which is comprised of a pair of inclined rolling rollers, a pair of travelling members respectively supporting the rolling rollers and a roll block supporter carrying a group of rolls on each of its side surfaces. Through the travel of the travelling members, the rolling rollers are adapted to move close to or away from each other. The rolling rollers press a 2g material ring cooperatively with the group of rolls, and a series of rolling operation is continuously performed through the rotation of the roll block supporter which rotates intermittingly every 90 degrees.
Johnson et al., U.S. Pat. No. 3,077,130 discloses this invention relates to rim rolling machines and refers more particularly to a rim rolling machine having a rim edge rolling attachment. The invention provides a rim rolling machine with specially contoured rolls to trim and smooth an edge of the rim blank; it also provides a rim rolling machine which has an attachment for rolling and smoothing an edge of the rim blank during the rim rolling operation and provides a rim rolling machine which has a rim edge rolling attachment that is automatically operated in timed relation with the rolls of the machine to roll an edge of the rim blank during the rim rolling operation.
Unfortunately, conventional roll grooving machines suffer from certain drawbacks. For example, they tend to be bulky, large and heavy causing them to be difficult to use. They tend to be complex machines and many are only useful for a narrow range of pipe diameters. Since pipe segments and tubes tend to be long with only one end engaged in the grooving machine, they must be supported along their length by one or more pipe stands, which is well known and conventional. A drawback of some conventional grooving equipment is that the grooving roller is positioned at the top of the tube to be worked. Therefore, when changing from one pipe diameter to another pipe diameter the vertical height of the pipe stands much be adjusted. The present invention avoids this inconvenience by placing the grooving roller at the bottom of the pipe. In this arrangement, the pipe stands are set for any pipe diameter. Another drawback of conventional grooving machines is that when grooving short pipe segments where no stand is required or necessary, the backup roller, which is inside the pipe does not materially contribute to the alignment of the pipe segment or to holding the pipe segment prior to clamping the pipe wall between the rollers. The presently described grooving machine has an extended length on the backup roller which provides this important enablement making the handling and grooving of short pipes and tubes much more convenient.